Underfeed stoker, including progressive overfeed grates



April 17, 1951 G. P. JACKSON 2,549,203

UNDERFEED STOKER, INCLUDING PROGRESSIVE OVERFEEP GRATES Filed Nov. 27, 1946 INVENTOR\ George P JaC/(SOU BY Ladfiwfew ATTORNEY 2 Sheets-Sheet 1 G. P. JACKSON UNDERFEED STOKER, INCLUDING PROGRESSIVE OVERFEED GRATES Filed Nov. 27, 1946 s fl 3 2 Sheets-Sheet 2 INVENTOR George/ Jae/52m MJOWM ATTORNEY Patented Apr. 17, 1951 UNDERFEED STOKER, INCLUDING PRO- GRESSIVE OVERFEED GRATES George P. Jackson, Flushing, N. Y., assignor, by

mesne assignments, to Combustion Engineering-Superheater, Inc., a corporation of Delaware Application November 27, 1946, Serial No. 712,479

2 Claims. (01. 110-47) I by the accompanying drawings wherein:

Figure 1 is a longitudinal section taken on line [-1 of Figure 2 through'a single retort stoker embodying the improved grate;

Figure 2 is a transverse section taken on line 2'-2 of Figure 1; and

Figure 3 is a partial half section, similar to Figure 2, showing a modification of the improved grate shown in Figure 2.

In the preferred embodiment of the invention a series'of grate members have their individual motions so inter-related that they produce an advancing movement of the fuel along the grate and a breaking-up action of the fuel bed. This action is particularly advantageous when burnf ing coking or caking coals.

Referring to Figure 1, beneath the usual fuel hopper at the front end of the stoker is a fixed plate ll over which a pusher l2 .reciprocates and pushes the fuel from the hopper through the throat l3 and thence into and through the retort l4. The retort 14 extends from the throat [3 to the rear of the stoker. A sliding bottom plate 15 at the bottom of the retort I4 rides upon fixed plate H and is reciprocated by a rod 16 fastened to plate 15 by a lug 11 which extends downwardly through a, slot I 8 in fixed plate I 1. Rod I6 extends forwardly through the stoker front 19 and is fastened to a cross head 20. Cross head 20 also is fastened to the pusher 12 by rod 2| and to the piston rod 22 which is fastened to the piston 23 within the cylinder 24.

As the piston is operated by a fluid under pressure to reciprocate, it reciprocates the pusher l2 and the sliding bottom plate l5. Mounted on the sliding bottom plate 15 is a wedge 25 which aids in advancing and distributing the fuel through the retort 14. There may be several such wedges 25 mounted longitudinally along the sliding bottom plate [5 depending upon the desired distrithe'grates 26 located on either side of the retort.

The grates are preferably symmetrically similar on both sides of the retort l4 and comprise a multiplicity of parallel rows of transversely aligned separate bars whose upper fuel-supporting surfaces slope generally downwardly from the retort 14 toward the furnace side walls 21. As shown in Figure 2, there are two such aligned bars in each row, a top bar 28 and a lower bar 29. Each of the upper bars 28 in the two side rows shown is supported at its inner end by the top side of retort.l4 which on each side of the retort is formed into a longitudinally extending shaft upon which the bearings 3| of bars 28 turn.

The outer ends of bars 28 rest upon the upper top surfaces of the lower bars 29. Lower bars 29 are supported at their inner ends by a longitudinally extending shaft 32 upon which the bearings 33 of bars 29 turn. The outer ends of bars 29 rest upon the top of outer plates 34 which are fastened to a Stoker frame member 35. The shaft 32 is connected by a number of arm-s 35 to a shaft 31, so that when the latter turns about its axis back and forth through a limited arc, the shaft 32 will oscillate through la, limited arc and raises and lowers the inner end of bar 29 through said arc. The outer end of the upper bar 28 which rests upon the lower bar 29 is in turn rotated up and down about its bearing 3|. An ash dump gate 38 of the usual type extends from the plate 34 to the wall 21 and is f astenedto a rocker shaft 39 which inturn is mounted to the stoker frame 35.

The shafts 31, one located at each side of retort l4 extendfrom the bearings 40 (see Figure 1) attached to the rear stoker frame 4! forwardly through the bearings 42 attached to the front stoker frame 43. On the forward end of each shaft is mounted a bevel gear 44 which meshes with a bevel gear 45 mounted on a lever '46 which is caused to oscillate through an are about the axis of bevel gear 45. Bearing means 41 support the gear 45 and the lever from the bottom side of hopper I ll.

The lower portion of lever 46 is provided with a longitudinal slot 43 within which slides a nut 49. A long-threaded bolt extends longitudinally of the slot, engages the nut 49 "and is mounted within the lever 45 so as to prevent any longitudinal movement with respect thereto. By turning bolt 50, the nut 49 may be moved radially along the slot 48 of the lever so as to increase or decrease the radial distance of the nut 49 from the bearing means 41. V 1

Attached to nut 49 is pin 51' which supports the rod being supported by pin '53 which is fastenedto cross head 2%). As the cross head 2E? reciprocates, the connecting rod 52 oscillates the lever t6 which, by means of bevel gears 45 and 44, causes shaft 31 to turn back and forth through an arc and thereby raises and lowers the inner ends of bars 29. By increasing or decreasing the radial distance of nut 49 from bearing means'dl, the movement of bar 29 may be proportionately decreased or increased.

In Figure 3 each row of transversely aligned bars comprises three members, an upper bar 28, an intermediate bar it and a lower bar 29. Like the upper bar in Figure 2, upper'bar 28' is con structed to hinge at its inner end, on the top tuyre side of shaft 30' in bearing 3| and to rest upon the intermediate bar 19 at its outer end. The intermediate bar it. is constructed to hinge at its inner end on the shaft 32' and to rest upon the lower bar 29 at its outer end. Shaft 32' is connected to rocker shaft 3'? by arms 36'.

The lower bar 29 of Figure 3, like the lower bar in Figure 2, is constructed to'hinge at its inner endlvia bearing 33') on a shaft 7 l and to rest upon the outer plate 3 at its outer end. The rocker shaft 37 is the equivalent of the rocker shaft 37 in Figure 2 andis turned back and forth through an are by means the same as those used for driving shaft 3?, and thereby raises and lowers the shaft 32 and the inner end of bar it. to shaft H by arms i=8. Rocker shaft 12 is similar to rocker shafts 3T, 37' and extends from the front to the rear of the stoker and is supported by'bearings in the front and rear stoker frames in the same manner as is shaft 31.

Rocker shafts 3'! and T2 are interconnected as by a connecting rod 13 and crank arms it and 15 (shown diagrammatically in'Figure 3), so that asshaft 31' turns back and forth through an arc, shaft I2 is caused to turn through a similar arc and. thereby lowers and raises the shaft H and the inner end of bar 29'. Rod 13 may be made adjustable in length by well known means so that the movement of rocker shaft 12 may be varied with respect to that of rocker shaft 3'? and thereby the movement of bar 29' with re-. spe'ct to that of bar 16.

In both Figures 2 and 3 the movements of bars 29, m and 29' may be varied by rotating the respective arms 36, 36' and IS with respect to rocker shafts 31, 31" and '52 from the positions spect to the direction of fuel movement and when moving downwardly push the fuel toward the.

The upward movement of both the a dump grate. upper bars 28 and lower bars Z9where they contact,lifts the fuel bed and breaks it thereabove I thereby breaking any coke masses that may have for example,"the shaft 31 turns clockwise and lowers the inner end of intermediate bars '10,

the shaft 12 turns counter clockwise and raises the outerend of said bar and consequently the bar it will tilt through a greater angle thanrthe remaining links. action of the fuel occurs at the juncture of intermediate bar Ill and the lowermost bar 29. By these combined motions the fuel bed is subjected to a greater breaking action than occurs with the bars of Figure 2.

Obviously different relative motions may be obtained between rocker shafts 31 Figure 3 by varying the. relative angular posi- The rocker shaft 12 is connected I tions of arms l4 and lip on their respective rocker shafts. In this manner dilfe'rent relative motions may be imparted to bars of the grate.

From the above disclosure, it may be seen that the relative movements of the links provide movements within the fuel bed which aid in push ving the fuel down the grate and inbreaking up objectionable coke formations within the bed.

. that the. bars may be easily. removed by lifting them off their supports from above without disturbing any other part of the stoker.

While the preferred embodiment of my invention has beenshown and described, it will be understood that minor changes in construction, combination and arrangement of parts may be made without departing from the spirit and scope 'of the invention as claimed. V

wardly from duct 57 (see Figure 2) ,into windbox Stand thence to boxes 59 and '58 through openings SI and 62. The amounts 'of air to theboxes F! and 62 are controlled by 'slidin'gdampers 6E; and E6 in-the openings fil andGZ. i 1

The relative extreme movementsof the grate bars Hand 29 in Figure 2 are shown by the full.

and dashed lines, The bars in their uppermost position are retracted toward the retort with re-,

, What I claim is: v

. 1. In a stoker, a retort extending longitudinally of the stoker, an overfeed grate comprising a multiplicity of parallel rows of bars extending transversely outwardly from one side of said retort and including at least three bars per'row, the bars in a row being aligned with the outer end of one bar overlying the inner e'nd of an adjacent bar; means for moving fuelfrom said retort onto said grate; a pivotal bearing at the underside portion of each of-the bars and at the inner end of each of the bars in-a row, the bear ings of the bars of each row being aligned longitudinally with the bearings" of the longitudinally 7 adjacent bars; all or the bars in said rows, ex-

cepting the outermost barsfbeing-freely sup- Furthermore a second liftingand 72 in V stoker and supporting the aligned pivotal bearings of all of said remaining bars; a rocker shaft for each of said bearing shafts spaced therefrom and parallel thereto, and arms connecting the rocker and bearing shafts; means for turning said rocker shafts back and forth through a predetermined angle including means for oscillating said rocker shafts in opposite directions to each other to thereby move the pivoted ends of the associated bars through oppositely rotating predetermined verticaily inclined arcs whereby to cause the relative movement of adjacent transverseiy aligned bars to agitate the fuel bed thereabove and to assist its advance along the grate.

2. In a stoker, a retort extending longitudinally of the stoker, an overfeed grate comprising a multiplicity of parallel rows of bars extending transversely outwardly from opposite sides of said retort and including at least three bars per row, the bars in a row being aligned with the outer end of one bar overlying the inner end of an adjacent bar; means for moving fuel from said retort onto said grate; a pivotal bearing at the underside portion of each of the bars and at the inner end of each of the bars in a row, the bearings of the bars of each row being aligned longitudinally with the bearings of the longitudinally adjacent bars; all of the bars in said rows excepting the outermost bars, being freely supported at their outer ends on the upper surfaces of the inner ends of the next adjacent outer bars; a plate freely supporting the outer ends of the outermost bars; means on said retort sides supporting the pivotal bearings of all of said innermost bars; shafts extending longitudinally of the 35 stoker and supporting the aligned pivotal bearings of all of said remaining bars; a rocker shaft for each of said bearing shafts spaced therefrom and parallel thereto, and arms connecting the rocker and bearing shafts; means for turning one of said rocker shafts back and forth through a predetermined angle; crank arms on said one rocker shaft and an adjacent rocker shaft; and adjustable connecting rods between said cranl; arms arranged to drive and reverse the direction of angular movement of said adjacent rocker shaft with respect to said one rocker shaft and to vary the angular locations of their respective arcs of rotation with respect to the associated bars, to thereby move the pivoted ends of the associated bars through oppositely rotating arcs having optionally difierent horizontal and vertical component movements whereby to cause the relative movements of adjacent transversely aligned bars to agitate the fuel bed thereabove and to assist its advance along the grate.

GEORGE P. JACKSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 724,872 Hurst Apr. 7, 1903 1,354,357 Wagoner Sept. 28, 1920 1,805,618 Foresman May 19, 1931 1,833,952 Priebe et a1 Dec. 1, 1931 2,335,549 Stark Nov. 30, 1943 FOREIGN PATENTS Number Country Date 54,215 Sweden June 6, 1923 648,153 Germany -1 July 23, 193,? 

